Iraqi Christians gathered for church services in Qaraqosh and Bashiqa, near Mosul in Niveneh province, for church services on 25 December.
These areas were recently retaken by the Iraqi army from Islamic State group (ISIL) control.
Many of those present were celebrating Christmas for the first time since 2013.
Practising Christianity was strictly forbidden for more than two years and most Christians fled the area when the militants seized power in 2014.
Meanwhile in Mosul itself, which remains partly under ISIL control, civilians continued to flee areas in the east of the city recaptured from ISIL, following counter-attacks from the militants.
Nearly 100,000 people have fled the city, according to the International Organization for Migration (IOM).